KB933566 Updated a file from w2k3 to vista ....

Hi

we´ve got the following problem:
Win2k3 Server R2 Sp2 with Citrix PS 4.5
if a user logs on its very sowly.

when i install "KB933566" a file named "iedkcs32.dll" is replaced.
before installation: Version "6.00.3790.3959
(srv03_sp2_rtm.070216-1710)" und "16.0.3790.3959" [it´s no mistake in
spelling!!!]
after ithe installation:Version 17.00.6000.16473 (vista_gdr.070420-1500)

If I replace the file with the old one (many ppeople say so) it works.

My question is:
1. why are ther two different versions in one file 16... and 6....
2. and why is there a file for ie7 vista on a windows 2003 server?????????

Dear Patrick